1. Field of Invention
The present invention relates to a mechanism for operating a cover that opens and closes the opening to a paper storage compartment rendered in a printer, and relates more particularly to improving the construction of a cover operating mechanism enabling a paper discharge guide or other moving member to open and close in conjunction with the cover opening and closing.
2. Description of Related Art
Roll paper printers used for printing receipts, for example, use roll paper having a single long web of paper wound into a roll as the recording (printing) medium. The roll paper supply mechanism used in such roll paper printers is often a so-called “drop-in loading” mechanism in which the roll paper simply rests and rotates freely on the bottom of the roll paper compartment instead of the roll paper being supported on a roll paper spindle that passes through the core of the roll so that the roll paper can rotate freely. This drop-in loading mechanism makes replacing or loading the roll paper easy because there is no need to mount or dismount the roll paper from the support spindle when replacing the roll paper.
With most drop-in loading roll paper printers opening the cover that opens and closes to access the roll paper compartment also opens the roll paper transportation path. When replacing the roll paper, the paper leader pulled from the roll paper must be set between a pair of paper transportation rollers, between the print head and the platen, and out from the paper exit. When the platen and paper feed rollers are opened together with the cover, the paper is pulled through the now open paper transportation path, and the cover is again closed, the printing paper is automatically threaded through the paper transportation path and ready for printing. The roll paper can thus be easily replaced and loaded in the transportation path by simply opening the cover, replacing the roll paper, pulling a leader out from the roll paper, and then closing the cover again.
A four-node parallel linkage mechanism is commonly used as the mechanism for opening and closing this operating cover in a roll paper printer rendered so that the paper transportation path can be opened by opening the cover. When the cover opens, the four-node parallel linkage mechanism and the platen fold together on the access cover so that the roll paper compartment can be opened widely. Japanese Unexamined Patent Appl. Pub. JP-A-2007-203563 and Japanese Unexamined Patent Appl. Pub. JP-A-2007-203564 teach roll paper printers having a drop-in loading roll paper supply mechanism that uses a four-node parallel linkage mechanism to open and close the paper transportation path in conjunction with the access cover.
The operating access cover of this type of roll paper printer includes a cover frame that is attached to the front parallel links of the four-node parallel linkage mechanism, and a cover case that covers the front side of this cover frame. The connection link connecting the front parallel links to the rear parallel links of this four-node parallel linkage mechanism is rendered by the platen frame, and a discharge guide for discharging the printed paper from the paper exit is attached to the front end of this platen frame. When the access cover is opened, the user unlocks the cover lock mechanism and then pulls forward on the discharge guide to open the cover.
For example, when an opening to the roll paper compartment is formed in the front of the printer, the access cover opens by pivoting at the bottom end thereof to drop forward from an upright closed position to an open position. When the cover opens, the cover pivots forward on a pivot point at its bottom end, and the discharge guide attached to the front end part of the platen frame moves forward while remaining level. The top end part of the cover case is positioned below the discharge guide. When the cover opens, the top end part of the cover case, which tilts forward pivoting at its bottom end, separates from the bottom of the discharge guide that moves forward while remaining level, and the gap between the top of the cover case and the discharge guide widens. Dust and other foreign matter can easily and undesirably enter the roll paper compartment through this gap.